Large oil spills occur regularly on lakes, oceans, estuary sounds and other bodies of water. Such environmental catastrophes are an unfortunate result of the mass transport of oil worldwide. The impact of an oil spill on the environment is directly and significantly related to the speed and comprehensiveness of the subsequent clean-up. If the method of clean-up requires a long time to initiate or proceeds slowly, then the oil tends to disperse and settle so that it is much harder or impossible to collect. If the method of clean-up tends to be incomplete, then the uncollected oil remains to harm the environment. Inefficient methods of clean-up involve great expense in addition to being slow and inadequate.
Water surface oil recovery methods generally have basic components in common. A confinement structure which floats on the surface and may extend somewhat into the water is generally used in conjunction with a collecting means. The confinement structure and collecting means are usually supported by a vessel or vessels which also house a separator system and a storage facility. As the confinement structure is towed or pushed across the surface of the water by the vessel or vessels, oil at the surface that comes within the path of the confinement structure is directed into the path of the collecting means. The collecting means serves to remove the oil and water at the surface. The collected oil and water are processed through the separator system. The separated oil is conveyed to the storage facility and the water is generally returned to the body of water.
Many methods and devices for recovering oil laying at the surface tend to be non-comprehensive and slow in water having waves. Most methods involve skimming the surface of the water with a fixed position collecting means. On a placid body of water, this method may have some measure of success. However, on water having waves, a fixed position collecting means is unable to remain at the water's surface. The collecting means usually lies too deep or too shallow in the water because it cannot adapt to the waves' crests and troughs. What is actually collected includes an undesirably large amount of water and air, and a limited amount of oil. This puts a great burden on the associated oil and water separator system and, because the rate of separation is the limiting factor in many designs, significantly slows the collection process. Unless the method includes some provision for collecting the large amount of oil not collected on the first pass, this oil remains in the body of water. Even with such provision, the collection is slowed, allowing the oil to disperse and settle, hence making the oil uncollectible. In addition to the damage done to the environment, the slow and inefficient methods described above cost man hours and fuel, and further damage the public image of the entity responsible for the oil spill.
Oil spills have several variable characteristics that must be taken into account to effectively recover the oil. The thickness of the oil layer determines how deeply the collecting means should skim in order to collect the most oil with the least water. Skimming too deeply overburdens the separator system by collecting too much water. Skimming too shallowly leaves oil behind and actually tends to disperse the oil. The temperatures in the water and the air influence the rate at which the oil can be collected and separated. Cold temperatures reduce the viscosity of the oil so that collection and separation are impeded. Present methods of oil skimming do not adequately account for and compensate for these factors.
Many methods and apparatuses for surface oil recovery include extensive collecting means and confinement structures which require several boats to tow them. Some recovery systems with less extensive collection means and confinement structures still cannot be practically moved at a high rate of speed because their collecting means and confinement structures cannot be disengaged from the water's surface. As previously discussed, speed is of the essence in cleaning up oil spills. A method or apparatus that requires several vessels to operate or requires the towing of a large structure through the water is necessarily slow. Such a method or apparatus is also expensive and inefficient. These methods are further slowed by the restricted maneuverability that results from having extensive and difficult to control collecting means and confinement structures. Where the oil spill is caused by a leaking vessel that continues to leak oil, it is often desirable to place the oil recovery apparatus close to or in contact with the leaking vessel. The aforementioned recovery apparatuses are often incapable of maneuvering into the necessary closed quarters, especially on rough waters.
There exists the need for a quick, maneuverable, efficient and effective method and apparatus for skimming oil or other immiscible liquids laying at the surface of a body of water. There exists an even greater need for such a skimming method and apparatus which is capable of effectively skimming oil on bodies of water having waves.